Here is an honest question.
Guns were easily available in the 60's=very few school shootings
Guns were easily available in the 70's= very few school shootings
Guns were easily less easily available in the 80's = a few more school shootings
Guns were more restricted and banned from schools in the 90's = School shooting becomes far more common
I don't think in the US this has ANYTHING to do with guns. Because the availability of firearms has become more restricted if anything and yet this type of incident is on the rise at an alarming rate. Firearms were far more common in American homes in the fifties, and they had firearms instruction at many HS, but nobody thought this was a way to make a name for themselves or solve their teen angst. So besides gun availability which hasn't changed. WHAT ELSE HAS CHANGED?
A few suggestions:
1) The importance that is placed on celebrity, and the fact that we have more people then ever who are famous and really haven't "done anything". That fifteen minutes thing seems to last a lot longer with incessant 24 hour news coverage.
2) The fact that as god is removed from the equation the rationality for values like compassion, equality, and individual human dignity, is on shakier ground, especially for those who are irrational in the first place.
3) The feeling that for many hedonism and materialism has replaced the thought of fear of some judgement in the afterlife. Again the rational keep the rules because they know society can't function with out it, not out of fear of an afterlife judgement. But what about a vast majority who don't even think about this stuff? How do they deal with crisis, when the fear of judgement is no longer part of their value system? To a person who sees no value in the rest of their life, no value in others, and sees no judgement, what rational argument is there against suicide or homicide?